Optical applications including lighting and displays have utilized optical couplers to convey light from a lamp or other light source to an output. Heretofore, optical couplers have generally been configured to receive light from a single light source.
Providing light from a single light source reduces the available brightness and the reliability associated with the lighting system. For example, a single light source cannot provide the brightness of two, three or more light sources, and when a single light source fails, the entire lighting system fails. Further, the lifetime of the lighting system can be increased by using multiple light sources and alternately engaging one of the multiple light sources.
One particular optical application which utilizes an optical coupler is an avionic or cockpit display. Avionic displays are used to display information to one or more users and can include a translucent plate for providing fixed information or an active matrix liquid crystal display (LCD) or projection display system for providing variable information. Such displays typically utilize a single arc lamp, or other tube-bused light source that provides light through an optical coupler to an output of the display. Such displays become unreadable or difficult to read if illumination from the optical coupler ceases. In avionic applications, a light source failure can cause an entire aircraft to be unoperationable or to be delayed for repairs. Accordingly, it is desirous to design lighting systems used in avionic displays to have a long lifetime and to be reliable.
Other display applications can be utilized with liquid crystal display technology found in portable computers, laptop computers, word processors, and avionic cockpit applications. It is desirous in those applications to have a reliable, bright lighting system.
In another optical application, a projection display system such as a projection television system, an overhead projector, or other display requires a light source which can provide high brightness. In these applications, it is also desirous to have a reliable, bright lighting system.
Thus, there is a need for lighting systems which can utilize an optical coupler capable of receiving light from multiple light sources. Further, there is a need for an optical coupler that is lightweight and compact for use in display and other lighting applications. Further still, there is a need for a display or lighting system having greater reliability and brightness capabilities. Yet further, there is a method for operating a display which achieves greater lifetime. Yet further still, there is a need for a method of manufacturing a lighting system which includes multiple light sources associated with multiple light paths that are combined into an integrated light path.